Embodiments of the present invention relate to process kit and target for a substrate processing chamber.
In the processing of substrates, such as semiconductor wafers and displays, a substrate is placed in a process chamber and processing conditions are set in the chamber to deposit or etch material on the substrate. A typical process chamber comprises chamber components that include an enclosure wall that encloses a process zone, a gas supply to provide a gas in the chamber, a gas energizer to energize the process gas to process the substrate, a substrate support to hold the substrate, and a gas exhaust to remove spent gas and maintain a gas pressure in the chamber. Such chambers can include, for example, CVD, PVD and etching chambers. In a PVD chamber, a target is sputtered to cause sputtered target material to deposit on a substrate facing the target. In the sputtering process, an inert or reactive gas is supplied into the chamber, the target is typically electrically biased, and the substrate maintained at an electrical floating potential, to generate a plasma in the chamber which causes sputtering of the target.
The PVD chamber can include a process kit comprising chamber components which are positioned the substrate support to reduce the formation of PVD deposits on the interior chamber walls or other regions. A typical PVD chamber process kit can include, for example, deposition, cover, and/or shadow rings, all of which are located about the periphery of the substrate. Various configurations of rings are arranged to receive sputtering deposits, which would otherwise accumulate on the side surfaces of the support or on the exposed backside surfaces of the substrate. The process kit can also include chamber shields and liners which protect the sidewalls of the chamber by serving as a receiving surface to receive PVD sputtering deposits which would otherwise deposit on the sidewalls of the chamber. The process kit components also reduce the accumulation of sputtered deposits on these surfaces, which would otherwise eventually flake off to form contaminant particles that deposit on the substrate. The kit components also reduce erosion of the internal chamber structures by the energized plasma. They can also be designed to be easily removable for cleaning of accumulated deposits. After processing of a batch of substrates, for example, 1000 substrates, the process kit components are typically removed and cleaned with an acidic solution comprising for example, HF and HNO3, to remove the sputtered deposits accumulated on the kit components during the substrate process cycles.
It is desirable to have a process kit comprising components that are shaped and arranged in relationship to one another to reduce the amounts of sputtered deposits formed on the internal walls of the chamber. Reducing the accumulated deposits allows a greater number of substrates to be sequentially processed in the chamber without requiring shutdown or dismantling of the chamber for cleaning. Each time, the chamber requires cleaning, the resultant downtime of the chamber increases the cost of processing the substrate. Thus it is desirable to maximize the amount of time the chamber can be operated to sputter material onto the substrate without shutting down the chamber to clean its internal surfaces.
Furthermore, in certain PVD processes, such as for example, aluminum PVD processes, the sputtered aluminum deposits accumulate in the gaps between the various deposition, cover, and other rings around the periphery of the substrate, and also form on the backside of the substrate. The accumulated sputtered deposits cause the substrate to stick to the deposition ring causing substrate damage when the substrate is attempted to be removed from the support. It is desirable to have rings which can reduce deposition on the backside of the substrate and side surface of the support without accumulating deposits on portions of the rings that cause the substrate to stick to the rings. It is also desirable to prevent a partially stuck deposition ring to rise with the substrate when the substrate is lifted from the support to reduce damage to the substrate and/or deposition ring.
Another problem arises when the liners and shields surrounding the substrate heat up with exposure to the sputtering plasma in the chamber. Typically, the shields and liners do not exchange a sufficient amount of heat with their surrounding chamber components in the low pressure environment within the chamber to lower the temperature of these components to acceptable levels. Excessive heating of these components is detrimental because thermal expansion of the components causes thermal stresses that result in peeling or spalling of the sputtered deposits formed on the shields and liners after a process cycle is completed. Thus, it is desirable to maintain the shields and liners at reduced or low temperatures during processing of the substrate.